This invention relates to an irrigation system for irrigating plants (including seedlings) in a controlled manner.
One system for this purpose, for small scale domestic use, is described in the specification of U.S. Pat. No. 4,475,307. In this system, there is a pivotally mounted reservoir for the liquid which is to be supplied to the plants. When swung about its axis to a first position, the reservoir is elevated with respect to a container accommodating the plants and the liquid is able to flow under gravity from the reservoir to the container. When a predetermined amount of liquid has been dispensed to the container, a counterweight urges the reservoir to swing back about the pivotal axis to a second position in which it is at a lower level than the container. Excess liquid now flows under gravity from the container to the reservoir for re-use when the reservoir is moved to its first position again.
While this system has proved successful in many applications, the fact remains that it is necessary to move the reservoir by hand each time a new irrigation cycle is to be commenced.
There are a number of features which a domestic irrigation system for the irrigation of plants should have in order to operate successfully. For instance, the periods and duration of irrigation cycles should be readily adjustable; the system should be capable of automatic operation, requiring little attention; excess irrigating liquid which is not consumed by the plants during each cycle should be capable of returning to a storage vessel for future use, thus reducing wastage and ensuring that there is sufficient irrigating liquid available for extended use; there should be means for ensuring a constant, predetermined level of liquid in the container in which the plants are situated; and the equipment should be safe, even when used outdoors. The last requirement is a particularly important one where the system makes use of electricity, since it is dangerous to have electrical components operating in the vicinity of liquids. Another important requirement of an efficient irrigation system is the capability to aerate the irrigating liquid prior to its being fed to the plants, since this leads to more efficient growth of the plants.
A number of different irrigation systems are shown in the prior art. In a number of prior art systems, the irrigating liquid is moved from a low level liquid vessel to a higher container accommodating the plants. In some cases, this is achieved with the use of a wicking material and capillary action. See, for example, UK patent application No. 2 113 963 A (Harris) and UK Pat. No. 1374647 (Sweetnburgh and Geyelin). Others make use of overhead sprays, which are, however, not suitable for irrigation in many cases. See, for example, U.S. Pat. No. 2,855,725 (Carothers). Others make use of conventional pumping arrangements, often automatically timed and controlled. See, for example, German Pat. No. 25 55 686 (Zink). Others make use of a gravity flow. See, for example UK patent application No. 2 009 574. Still others achieve aeration of the irrigating liquid. See, for example, U.S. Pat. No. 4,057,933 (Enyeart).
The present invention seeks to provide an irrigation system suitable for domestic use and which, at least in some embodiments, exhibits the advantageous features listed above.